Resident Or Non-resident?

Well, I've digested all the info on this forum about the requirements etc for being resident or non-resident in Thailand? I need to make a decision on this and just want to check that I havn't missed anything!

I'm British, and live in Thailand for 3 weeks in each month, returning to the UK for the 4th week. I have a multiple-entry non-immigrant B visa. I have a Thai GF but we are not married, nor is this likely in the near future. I own land in Thailand (via my Thai ltd company), and am buying a condo in my name.

I'm just sorting out a work-permit. I don't actually 'work' in Thailand (by previous definitions on this forum), but the WP is really needed since I am the sole director of my Thai company.

It has been suggested to me that I go for a 1 year residency permit. That would mean that my WP would be valid for 1 year also, and then be extended each year. But I would presumably need to bank 400,000 baht or so in a Thai bank account (which I don't really want to do ). If I remain non-resident, then the 400,000 is not required, but my WP must be extended every 90 days.

My visits to the UK each month will always continue (I have young kids there). To my naive mind, it seems that I am better off to remain non-resident. But can anyone more knowledgable than me make a bullet-point list of pros and cons of being resident and non-resident?

cheers - Simon